Volunteering is the right thing to do -- we all know that. And studies show that it boosts happiness; those who work to further causes they value tend to be happier and healthier, experience fewer aches and pains, and even live longer. And it's not just that helpful people also tend to be healthier and happier; studies show that helping others itself causes happiness. "Be selfless, if only for selfish reasons," as one of my happiness paradoxes holds. About a quarter of Americans volunteer, and of those, a third volunteers for more than a hundred hours each year (which requires just two hours each week).

One cause for which I volunteer my time, energy, and money is the New York Public Library. I love the NYPL! Whether you want an excellent book to read, help updating your resume, a great place for your teen to go after school, or research materials for the Ph.D. you're writing about the history of the French Revolution, you find people and resources to help you -- and all for free.

And just as the research predicts, my bit of work for the Library has made me so happy. I've met so many terrific people who share my love of reading and research. I've learned about treasure troves of books and materials that I never knew existed. I've drawn closer to New York City.

Do you need some help figuring out how to volunteer? Many great organizations match volunteers with opportunity. For example, Catchafire -- "give what you're good at" -- is a site that, in just a year, has become the largest pro bono ("for the public good") service provider in New York City, with more than 5,000 professionals giving pro bono.

One of the most pernicious myths about happiness is that it's selfish to try to be happier. In fact, research -- and experience -- prove just the opposite. Happy people take greater interest in the problems of the people around them, and in social problems. They spend more time helping others, and are more likely to volunteer and to give away money. Happiness gives people the emotional wherewithal to turn outward, while the less happy are more likely to feel distrustful, isolated, and preoccupied with their own needs. So if it's selfish to be happy, we should aim to be happy, if only for selfless reason.

To put this argument more succinctly, the Second Splendid Truth holds:

One of the best ways to make yourself happy is to make someone else happy;

One of the best ways to make someone else happy is to be happy yourself.

Do you volunteer your time and skills? To what? Does it make you happier?

I'm part of Catchafire's Powerful Woman campaign in support of National Volunteer Week. To give your times and skills to a cause you love, go to Catchafire.

* April is National Volunteer Month, and it's also Donate Life Month. Kill two birds with one stone by volunteering to donate life! Volunteer as an organ donor by signing the online donor registry. Live your values. Do good, feel good.

* Sign up for the Moment of Happiness, and every weekday morning, you'll get a happiness quotation in your email inbox. Sign up here, or email me at gretchenrubin1 at gmail dot com.